1. Field of the Invention
The present invention relates to a barrier seal for use with an electrostatic chuck in a plasma etching equipment, and more particularly to a barrier seal that may be mounted into a groove of the electrostatic chuck with multiple sealing portions.
2. Description of the Related Art
Conventional plasma etching equipment is shown in FIG. 9. The plasma etching equipment comprises an electrostatic chuck 90. The electrostatic chuck 90 comprises an upper element 91 which is made of dielectric ceramic materials, a bottom element 92, and a soft connecting layer 93. The connecting layer 93 connects to the upper element 91 and the bottom element 92. The electrostatic chuck 90 further comprises an extending element 100 around the electrostatic chuck 90. There are a gap 110 and a groove 113 between the electrostatic chuck 90 and the extending element 100. Plasma gas 120 can flow into the space between the electrostatic chuck 90 and the extending element 100 through the gap 110, and the plasma gas 120 further permeates into the groove 113 and destroys the connecting layer 93 to induce the erosion of the electrostatic chuck 90 and a leaking point in the plasma etching process. The working fluid in the electrostatic chuck 90 may flow out to the exterior of the electrostatic chuck 90 through the leaking point and induce pollution of the environment.
In order to resolve said problems, disposing epoxy 130 in the groove 113 is a skill in the art as shown in FIG. 10. The groove 113 is filled by the epoxy 130 to prevent the damage of the connecting layer 93 by the plasma gas 120. However, the epoxy 130 is eroded easily and becomes thinner by the plasma gas 120. After plasma etching for a long term, a leaking point is formed and the epoxy 130 loses its protection function gradually. In addition, the lifetime of the epoxy 130 is hard to estimate. Engineers may not timely block the leaking point before the gas leak happens.
Another skill in the art provides a replaceable elastomer ring 140 to substitute for the epoxy 130 as shown in FIG. 11. The elastomer ring 140 may overcome the above problems of the epoxy 130. However there is only a sealing portion 150 between the connecting layer 93 and the groove 113. The size of the groove 113 is very small. It is hard to install the elastomer ring 140 into the groove 113 evenly. As the elastomer ring 140 cannot be disposed in the groove 113 evenly, engineers may hardly estimate the lifetime of the elastomer ring 140. When the elastomer ring 140 is unable to block the connecting layer 93, the erosion of the connecting layer 93 and the pollution will be induced. Many problems still exist in sealing the groove 113 of the electrostatic chuck 90 in a plasma etching equipment.